Score doesn't matter too much, as some players (myself included) have inflated scores due to the use of Base Space Yards and Light Carriers (instead of planetary Space Yards and Light Cruisers). Your number of colonies does matter a lot however.
I cannot give a definitive advice, save saying how I do *my* expansion early on (I am reluctant to say "my", since my way is virtually the same as Primitive).
- Put your homeworld on Emergency Build straight ahead, and queue eleven Colony ships to be built in one turn. If you don't have enough in Construction aptitude, and/or a poor homeworld, you will need to use a retrofit (for example, use a Colony ship hull with the module and the necessary, and add the engines with a retrofit).
- Your colony ships will act as scouts on their way; you will likely lose one or two to black holes, or enemy fire if you are unlucky. If you are afraid of the possibility of capture, give them Kamikaze orders so that they will ram the enemy (destroying themselves in the process).
- Colonise far away, at least two systems away from your homeworld to begin with. Unless you need to secure a planet at once, go for the small, unbreathable planets first. Then, build a planet Space Yard, and use this planet to get more colony ships even further away from home. Only colonise close planets to get more minerals, and above all, organics and radioactives.
- Construction and Mines I should be your priority early on. Unless you start very close to someone else, you should have Mines by the time you make contact. They can be rather nasty to secure other planets in the system, and to deter any raider.
Also note that you will likely have an impressive income through trade treaties if playing in big games, so it will help lessening the gap with these big Empires.
Lastly, sheer colonial size does not spell the game; your lesser size can be used to strengthen your defence, whereas a big Empire has to deal with logistics and possible riot runs (when your two farthest colonies are twenty turns away from one another, you will have a hard time protecting both). If you are in peace with your neighbours, you should have a lot of resources through trade, allowing you to build many Base Space Yards later on, and so a nasty fleet. Then, you will hopefully be better than me to handle said fleet, and so you may be the one bringing my huge Empire to its knees.
Oh, my Last usual remark: never overlook Stellar Manipulation. If there are many Asteroid Fields nearby, you will want to consider creating Planet Shapers, increasing your economical strength quite a lot in the meantime. Likewise, Warp Openers and Warp Closers can turn the tides of a war if you are the only one with these technologies available. And in the end, what about the ever-so funny Star Destroyer?
